Grindstone for grinding or smoothing lithographic stones.



, PATENTED MAY 5 o. REUGHLIN; I GRINDSTONE FOR GRINDING 0R SMOOTHING LITHOGRAPHIG STONES.

lNVENTBR.

.APPLIOATIQN FILED JUNE 6. 1907.

O m T T E a THE NaRR/s PETERS :0

UNITED STATES PATENT OFFICE.

OSCAR REUCHLIN, OF STUTTGART, GERMANY.-

GRINDSTONE FOR GRINDING OR SMOO'IHING LITI IOGRAPHIC STONES.

Application filed June 6, 1907.

T 0 all whom it may concern:

Be it known that I, OSCAR REUOHLIN, a citizen of the German Empire, residing at Stuttgart, in the Kingdom of Wurtemberg, Empire of Germany, have invented certain new and useful Improvements in Grindstones for Grinding or Smoothing Litho graphic Stones, of which the following is a description, reference being had to the accompanying drawing and to the letters and figures of reference marked thereon.

This invention has for its object a combination or compound grindstone for grinding or smoothing lithographic stones by hand.

It has hitherto not been possible with the ordinary grindstones to grind or smooth lithographic stones so as to be quite ready for printing, as the fine grit which is in all emery grinding wheels leaves on the ground lithographic stones a small grain Which has hitherto been removed by the lithographic stones, after being smoothed or ground by means of an ordinary emery grinding wheel, being subsequently ground with natural lava pumice or other artificial pumice.

Now this improved combination grindstone consists of an ordinary emery dust grinding wheel provided with perforations, and an artificial pumice stone let into it, and is shown in the accompanying drawings in which Figures 1 and 2 are vertical sectional views; and Fig. 3 a plan view.

The emery dust grindstone a which is pro- Specification of Letters Patent.

Patented May 5, 1908.

Serial No. 377,479.

vided with recesses c has an insertion b of natural lava pumice or artificial pumice stone, and the result is thereby attained that in grinding a lithographic stone a floury slime free from grit is formed which in combination with the emery dust of the grindstone polishes the lithographic stone quite smoothly. Any re-grinding is thus avoided and a considerable saving of time and money is efiected and a long desired requirement fulfilled.

The pumice insertion may be of any suitable form and it is preferably cast into the emery grindstone at the same time as the latter is made. Of course, in place of one pumice stone, several such may also be employed as insertions.

I declare that what I claim is A combination hand grindstone for grinding andsmoothing lithographic stones, composed of a tubular block of emery, combined with a smoothing body consisting of an insertion of pumice stone securely fitting within the tubular part of said block, and the edges of the block together with the face of the insertion constituting the working surface of the grindstone.

In testimony whereof I afiix my signature, in presence of two witnesses.

OSCAR REUOHLIN.

Witnesses JEAN GULDEN, HERMANN HOPPE. 

